Ligament origins are preserved in distal radial intraarticular two-part fractures: a computed tomography-based study

Displaced dorsal rim fragment in distal radius fracture: what is the size threshold for compromise?

INTRODUCTION

This study aimed to explore the effect of displaced dorsal rim fragments under defined size threshold on the clinical outcome.

MATERIALS AND METHODS

Forty patients with an acute distal radius fracture accompanied by a dorsal rim fragment comprising less than 10% of the radiocarpal articular surface were included in the study. The size of the dorsal rim fragment was measured by axial CT scans and three-dimensional (3D) CT scans, and the correlation between these two methods was analyzed to evaluate the reliability of axial CT scan measurements. Based on the displacement (> 2 mm) of dorsal rim fragments measured by sagittal CT scans, the patients were divided into two groups, namely the displaced group (17 patients) and the control group (23 patients). The radiographic parameters and wrist function at final follow-up were compared between the two groups.

RESULTS

Mean radiocarpal joint involvement of the included dorsal rim fragment was 8.6%±1.0% (range, 5.7-9.9%) assessed by axial CT scans. There was a strong correlation in the radiocarpal articular involvement of the dorsal rim fragment between axial CT scans and 3D CT models (correlation coefficient r = 0.819). Mean displacement of the dorsal rim fragment was 2.2 (2.1, 2.5) mm (range, 2.0-3.2) in the displaced group and 0.9 (0, 1.5) mm (range, 0-1.9) in the control group. There were no significant differences in any radiographic parameter and wrist function between the two groups.

CONCLUSIONS

For dorsal rim fragments comprising less than 10% of the radiocarpal articular surface in distal radius fracture, mild displacement does not significantly affect the recovery of wrist function.

A proposal for name-tagging three-dimensional distal radial fracture fragments based on preliminary results

Melone introduced a classification system for distal radial fractures, emphasizing the intra-articular patterns. We explore the significance of key part fragments and introduce a three-dimensional fracture tagging system based on an updated version of Melone's concept.

[Diagnostics and classification of distal radius fractures]

Fractures of the distal radius show a wide spectrum of different fracture patterns. Although standard X‑ray images are sufficient for extra-articular fractures, the exact analysis of intra-articular fractures requires the use of computed tomography (CT) with coronal, sagittal and axial sectional images. The classification is based on the Working Group for Osteosynthesis Questions (AO) criteria. The treatment strategy can be more precisely defined by a CT-based classification. Special attention must be paid to the presence of the key corners, as they have a high risk for primary or secondary dislocation if they not adequately stabilized.

Establishment and preliminary evaluation of CT-based classification for distal radius fracture

Establish a new classification system of distal radius fracture based on computed tomographic (CT), and evaluate its reliability and reproducibility preliminarily, and provide a new theoretical reference for clinicians to use the clinical classification system. The imaging data and clinical data of 204 inpatients with distal radius fracture during 6 years from January 1, 2014 to January 1, 2019 in orthopaedic department were analyzed retrospectively and classified based on CT. Three observers evaluated the image data of 48 randomly selected cases based on CT at different time nodes of T1 and T2. Cohen's kappa was used to calculate the consistency. At the last follow-up, patients' Disabilities of the Arm, Shoulder and Hand (DASH), Patient Rated Wrist Evaluation (PRWE), and VAS scores were collected. Among 204 cases, there were 12 cases of type 1, including 6 cases of type 1-D, 4 cases of type 1-V and 2 cases of type 1-R. There were 6 cases of type 2, including 2 cases of type 2-DV, 2 cases of type 2-DR and 2 cases of type 2-VR. There were 186 cases of type 3, including 32 cases of type 3-0, 127 cases of type 3-1 and 27 cases of type 3-2. There was no significant difference in DASH, PRWE and VAS scores among all types (P > 0.05). The results of interobserver reproducibility were kappa = 0.985, ICC = 0.984 in the first evaluation, kappa = 0.986, ICC = 0.986 in the second evaluation. The results of intraobserver reproducibility were O1 = 0.991, O2 = 0.991, O3 = 0.989 respectively. The new classification system of distal radius fracture based on CT has theoretical and practical significance for incision selection, fracture reduction and internal fixation. 123 classification system is clear, comprehensive, easy to understand and remember. Moreover, it has higher interobserver reliability and intraobserver reproducibility than other systems reported at present.

CT-Based Micromotion Analysis After Locking Plate Fixation of AO Type C Distal Radius Fractures

Background

Volar locking plate fixation (VLPF) is the most common method for operative fixation of distal radius fractures (DRF). The dorsal ulnar corner (DUC) can be difficult to stabilize as the fragment is small and not exposed when using the volar approach. The purpose of this study was to study fracture fragment migration after VLPF of AO type C DRF, using a volume registration technique of paired CT scans with special focus on the DUC fragment.

Materials and Methods

This pilot study included ten patients with AO type C DRF, all operated with VLPF. The primary outcome was radiographic outcome. Postoperative and 1-year scans were compared and analyzed. Fragment migration was assessed with CT-based micromotion analysis (CTMA), a software technique used for volume registration of paired CT scans.

Results

All plates were stable over time. Two patients showed signs of screw movement (0.2-0.35 mm and 0.35- > 1 mm respectively). Postoperative reduction was maintained, and there was no fragment migration at the 1-year follow-up except for one case with increased dorsal tilt. The DUC fragment was found in 8/10 cases, fixated in 7/8 cases, and not dislocated in any case at the 1-year follow-up.

Conclusion

The CTMA results indicate that variable-angle VLPF after AO type C DRF can yield and maintain a highly stable reduction of the fracture fragments. The DUC fragment remained stable regardless of the number of screws through the fragment. CT volume registration can be a valuable tool in the detailed assessment of fracture fragment migration following volar plate fixation of DRFs.

[Distal radius fracture-tactic and approach]

OBJECTIVE

The aim of surgical treatment is fracture healing with restored alignment, rotation, and joint surface. Stable fixation allows for functional postoperative aftercare.

INDICATIONS

Displaced intra- and extra-articular fractures which either could not be adequately reduced or in which a secondary displacement is to expected due to instability criteria. The following factors are considered instability criteria: age > 60 years, female, initial dorsal displacement > 20°, dorsal comminution, radial shortening > 5 mm, palmar displacement.

CONTRAINDICATIONS

The only absolute contraindication is if the patient is deemed unfit for surgery due to concerns regarding anesthesia. Old age is a relative contraindication, as it is currently debated whether older patients benefit from the operation.

SURGICAL TECHNIQUE

The surgical technique is guided by the fracture pattern. Palmar plating is most commonly performed. If the joint surface needs to be visualized, a dorsal approach (in combination with another approach or alone) or arthroscopically assisted fixation should be chosen.

POSTOPERATIVE MANAGEMENT

In general, a functional postoperative regime can be carried out after plate fixation with mobilization without weightbearing. Short-term splinting can provide pain relief. Concomitant ligamentous injuries and fixations, which are not stable enough for functional aftercare (such as k‑wires) require a longer period of immobilization.

RESULTS

Provided the fracture is reduced correctly, osteosynthesis improves functional outcome. The complication rate ranges between 9 and 15% with the most common complication being tendon irritation/rupture and plate removal. Whether surgical treatment holds the same benefits for patients > 65 years as for younger patients is currently under debate.

Radiographic Outcomes for Comminuted, Intra-articular Distal Radius Fractures Treated with Primary Distraction Bridge Plate Fixation

Purpose

To determine if distraction bridge plate (DBP) fixation as the primary method of stabilization can effectively correct and maintain acceptable radiographic parameters in the treatment of comminuted, intra-articular distal radius fractures while allowing early load-bearing.

Methods

A retrospective review was performed of all consecutive intra-articular distal radius fractures that underwent DBP fixation with or without supplemental fixation methods (fragment-specific implants or K-wires). Patients treated with a volar locked plate in addition to DBP were excluded. Radiographic outcomes measures included volar tilt (°), radial height (mm), radial inclination (°), articular step-off (mm), lunate-lunate facet ratio (LLFR), and teardrop angle (°) measured on post-reduction, immediately post-operative, prior to and after DBP removal.

Results

Twenty-three comminuted, intra-articular distal radius fractures were treated with primary DBP fixation. Supplemental fixation was utilized in 10 fractures and included fragment-specific implants (n = 6) and/or K-wires (n = 5). Distraction bridge plates were removed after a mean of 13.6 weeks. At a mean radiographic follow-up of 11.4 weeks (range: 2-45 weeks) following DBP removal, all fractures had united with a mean volar tilt of 6.3° ± 5.8°, radial height of 11.3 ± 2.3 mm, radial inclination of 20.2° ± 4.5°, articular step-off of 0.6 mm ± 0.8, and LLFR of 1.05 ± 0.06. However, the teardrop angle could not be restored to a normal value with DBP fixation. Complications included 1 plate breakage and 1 peri-hardware radial shaft fracture.

Conclusion

Distraction bridge plate fixation is a reliable method to stabilize highly comminuted, intra-articular distal radius fractures in patients with a well-aligned volar rim fragment of the lunate facet.

Graphical Abstract

Volar Lunate Facet Fractures of the Distal Radius: Fracture Mapping Using 3D CT Scans

Background  Fractures of the distal radius involving the lunate facet at the volar articular surface are unstable injuries and are usually managed operatively. Management of these fractures is challenging as our understanding of the exact fracture characteristics and associated injuries to the carpus is poor. Purpose  This study aims to define the anatomy and associated injuries of lunate facet fractures using three-dimensional computed tomography (CT) scans and fracture mapping techniques. Methods  A consecutive series of CT wrists was analyzed to identify intra-articular fractures involving the lunate facet at the volar distal radius. Fractures were mapped onto standardized templates of the distal radius using previously described fracture mapping techniques. We also identified instabilities of the carpus including volar carpal translation, ulnar translocation, scapholunate diastasis, and distal radioulnar joint (DRUJ) instability. Results  We present 23 lunate facet fractures of the distal radius. The lunate facet fragment displaces in a volar and proximal direction and the lunate always articulates with the displaced fragment. The smaller fragments displace a greater amount, in a volar direction, with pronation. The fracture tends to occur between the origin of the short and long radiolunate ligaments. Conclusion  Lunate facet fractures are frequently comprised of osteoligamentous units of the distal radius involving the short and long radiolunate ligaments and the radioscaphocapitate ligament. Assessment and management of volar carpal subluxation, scapholunate instability, ulnar translocation, and DRUJ instability should be considered. Clinical relevance  Our mapping of these fractures contributes to our understanding of the anatomy and associated instabilities and will aid in surgical planning and decision making.

Gantry-Free High-Resolution Cone-Beam CT: Efficacy for Distal Radius and Scaphoid Fracture Detection and Characterization

OBJECTIVES

Gantry-free cone-beam CT (CBCT) allows for comfortable patient positioning due to an open scanner architecture. Since CBCT without gantry is not yet established for clinical wrist trauma imaging, this study's aim was to investigate its diagnostic value in the preoperative workup of patients with distal radius and scaphoid fractures.

METHODS

Within a 12-month period, 113 patients with severe wrist trauma underwent both radiography and CBCT with the same gantry-free multi-use scanner before surgery. Two radiologists retrospectively analyzed all datasets for the morphology of distal radius (n = 95) and scaphoid fractures (n = 20). In all 115 wrists (two bilateral injuries), surgical reports served as the standard of reference.

RESULTS

While accuracy for distal radius fractures was comparable among CBCT and radiographs, the former was superior with regard to scaphoid fractures (Reader 1: 100.0% vs. 75.0%; Reader 2: 100.0% vs. 65.0%). Accuracy for multi-fragmentary radius injuries (100.0% vs. 90.5%; 100.0% vs. 93.7%), and articular affliction (99.0% vs. 84.2%; 100.0% vs. 83.2%) was also higher in CBCT. Regarding scaphoid fractures, CBCT proved superior for diagnosis of proximal pole or waist involvement (100.0% vs. 70.0%; 100.0% vs. 65.0%) and comminuted patterns (100.0% vs. 70.0%; 100.0% vs. 75.0%). Median effective dose of CBCT was as low as 3.65 µSv compared with 0.16 µSv for standard radiography.

CONCLUSION

Gantry-free CBCT allows for excellent diagnostic accuracy in the assessment of distal radius and scaphoid fracture morphology. Even in patients with limited mobility, very low radiation dose is sufficient to maintain high image quality.

Treatment of distal radius fractures using a cemented K-wire frame

BACKGROUND

This retrospective study included an alternative treatment for types A2, A3, and B1 distal radius fractures using percutaneous fixation with a cemented K-wire frame.

METHODS

From January 2017 to January 2020, 78 patients with distal radius fractures were treated with percutaneous internal fixation using a cemented K-wire frame. There were 47 male patients and 31 female patients. The fractures were classified into types A2 (n = 10), A3 (n = 46), and B1 (n = 22). X-rays were taken immediately after surgery and after the bone had healed. Wrist function was assessed using the Mayo Wrist Score (90-100, excellent; 80-90, good; 60-80, satisfactory; < 60, poor). Patient satisfaction was assessed using the 10-cm visual analog scale.

RESULTS

Neither fixation failure nor K-wire migration was found (P > 0.05). Osteomyelitis was not observed in this series. All patients achieved bone healing after a mean of 4.5 weeks (range, 4 to 8 weeks). Follow-up lasted a mean of 27 months (range, 24 to 33 months). The mean score of wrist function was 97 (range, 91 to 100). Among them, 66 results were excellent and 12 results were good. The mean patient satisfaction was 10 cm (range, 8 to 10 cm).

CONCLUSIONS

Percutaneous fixation with cemented K-wire frame is a safe and preferred choice for the treatment of types A2, A3, and B1 distal radius fractures. The frame provides support to prevent wire migration. The fixation technique is a minimally invasive procedure that is easy to perform.

LEVEL OF EVIDENCE

Therapeutic study, Level IVa.

Computed Tomography and Pathobiomechanical-Based Treatment of Volar Distal Radius Fractures

Today, there are various classifications for distal radius fractures (DRF). However, they are primarily based on plain radiographs and do not provide sufficient information on the best treatment option. There are newer classifications that simultaneously consider the pathobiomechanical basis of the fracture mechanism and analysis of computed tomography images. Main determinants of which type of DRFs occurs are the strength/direction of the applied forces on the carpus and radius, and the position of the wrist relative to the radius during the fall. Reconstruction of the mechanism of injury provides information about which anatomic structures are involved, such as torn ligaments, bone fragments, and the dislocated osteoligamentous units. This article attempts to combine and modify current pathobiomechanically oriented classifications with an improved understanding of the "key fragments" to subsequently offer a treatment approach to stabilize these critical fragments through specific types of internal fixation.

Anatomical and Clinical Concepts in Distal Radius Volar Ulnar Corner fractures

Background  Volar ulnar corner fractures are a subset of distal radius fractures that can have disastrous complications if not appreciated, recognized, and appropriately managed. The volar ulnar corner of the distal radius is the "critical corner" between the radial calcar, distal ulna, and carpus and is responsible for maintaining stability while transferring force from the carpus. Description  Force transmitted from the carpus to the radial diaphysis is via the radial calcar. A breach in this area of thickened cortex may result in the collapse of the critical corner. The watershed ridge (line) is clinically important in these injuries and must be appreciated during planning and fixation. Fractures distal to the watershed ridge create an added level of complexity and associated injuries must be managed. An osteoligamentous unit comprises bone-ligament-bone construct. Volar ulnar corner fractures represent a spectrum of osteoligamentous injuries each with their own associated injuries and management techniques. The force from the initial volar ulnar corner fracture can propagate along the volar rim resulting in an occult volar ligament injury, which is a larger zone of injury than appreciated on radiographs and computerized tomography scan. These lesions are often underestimated at the time of fixation, and for this reason, we refer to them as sleeper lesions. Unfortunately, they may become unmasked once the wrist is mobilized or loaded. Conclusions  Management requires careful planning due to a relatively high rate of complications after fixation. A systematic approach to plate positioning, utilizing several fixation techniques beyond the standard volar rim plate, and utilizing fluoroscopy and/or arthroscopy is the key strategy to assist with management. In this article, we take a different view of the volar ulnar corner anatomy, applied anatomy of the region, associated injuries, and management options.

Distal radius fractures

The management of distal radius fractures has evolved considerably in the last two decades. Techniques and hardware have improved so much that the surgeon can usually assure good results in these debilitating fractures. Yet no one method can be used for all injuries, as the personality of each fracture demands a customized approach. Furthermore, what works in one age group may not work in another. For this reason, every available treatment has its own space in our options. The need for surgeons to be well versed in all techniques is critical. We offer a concise update of important evolutionary and current treatment guidelines for this common fracture.

Distal Radioulnar Joint, Distal Ulna Injury, and Lunate Facet Considerations in Distal Radius Fractures

Injuries to the distal aspect of the ulna and the distal radioulnar joint (DRUJ) commonly occur concurrently with distal radius fractures. These fractures may also involve the sigmoid notch of the lunate facet of the radius. Each of these structures merits consideration when managing ulnar-sided injuries associated with distal radius fractures. Improper management of distal radioulnar complex injuries may result in limited wrist motion, persistent DRUJ instability, and pain despite successful fracture union. The distal ulna is the keystone of the distal radioulnar articulation. An understanding of the components of the distal radioulnar complex and methods to manage injuries of each of these components contributes to improved functional outcomes by restoring this keystone effect. The classification of distal radioulnar injuries discussed herein provides a framework for understanding the disruption of the ligamentous stabilizers of the DRUJ and identifying residual distal radioulnar instability after fracture fixation. Proper treatment of residual DRUJ instability will restore stability and minimize persistent functional impairment.

Conservative treatment of ulnar styloid fractures following volar-plate fixation of distal radius fractures: incidence of nonunion evaluated by computed tomography

PURPOSE

The first aim of this study was to investigate the incidence of ulnar styloid fractures (USFs) accompanied by distal radius fractures (DRFs), treated with volar locking plates. The fracture type of DRFs was evaluated by the classifications, based on computed tomography (CT) scan findings. The second aim was to investigate the bone union rate of USFs, depending on the fracture type of DRFs, by comparing union and nonunion groups in the USFs groups.

METHODS

Between May 2012 and December 2019, 239 consecutive patients with DRFs were treated. Of these patients, 177 DRFs met inclusion criteria. The fracture patterns of the DRFs, based on the classification, using CT scans, which included the AO classification, sagittal angulation, and axial fracture patterns of the articular surface of the distal radius in two-part intra-articular fractures were evaluated. The size of USFs, classified as a tip or base fracture was also investigated.

RESULTS

The incidence of USFs was significantly higher for AO types A and C than for type B. Analysis of the sagittal angulation of DRFs showed that the incidence of USFs was higher for the extension type than for the flexion type. Axial CT classification of two-part fractures revealed that DRFs with a dorsal fracture line was more frequent than the volar type of DRFs. These results suggested that dorsal displacement of DRFs was associated with a higher incidence of USFs. Finally, the analysis of the bone union rate of USFs revealed that AO classification and sagittal angulation were not correlated with bone union in USFs. However, it was found that a fracture line on the radial side of the radius had a significantly low rate of bone union, compared to a fracture line on the dorsal side. The size of USFs was also not correlated with the bone union rate.

CONCLUSIONS

The incidence and the bone union rate of USFs have different patterns. The incidence of USFs was higher in the dorsal displacement type of DRFs. However, the bone union rate of USFs was lower for a fracture line on the radial side. Therefore, USFs with DRFs that have a fracture line on the radial side is a candidate for fixation to prevent nonunion.

Fragment specific fixation with APTUS wrist system for volar rim fractures of the distal radius: a multicentric study

PURPOSE

Volar rim fractures of the distal radius are a spectrum of pathology that must be well identified and treated to achieve good outcomes and avoid surgical failures. New devices of fragment specific fixation have been developed during the last decades to fix this fragment. The purpose of this retrospective study was to evaluate the ability of APTUS^® wrist distal radius system to securely fix different types of volar rim fractures.

METHODS

Patients with at least 1 year of follow-up and a preoperative CT-scan evaluation of the fracture pattern were included in the study. Clinical, radiological and functional outcomes were assessed.

RESULTS

Sixty-eight patients with an average follow-up of 34, 1 months (12-61) were included in the study. There were no clinical and radiological complications, including loss of reduction, device failure and tendon ruptures. No patients required hardware removal. Wrist range of motion in flexion-extension averaged 96°, while in pronation-supination 144°. At final follow-up mean visual analogue scale pain was 1,8. Questionnaires, as dissabilities of the arm, shouldder and hand (DASH) score and patient-related wrist evolution (PRWE) score were 6,6 and 3 respectively. Grip strenght measured 86% compared to the normal side.

CONCLUSION

APTUS^® wrist presents a versatile set of fragment specific fixation plates able to easily and securely fix all types of volar rim fracture. The system can be used with other devices without any kind of interference between them. When correctly placed and used with the right indications, no late complications can be recorded.

Scapholunate Diastasis in Distal Radius Fractures: Fracture Pattern Analysis on CT Scans

Objectives  Our understanding of distal radius fractures with concomitant scapholunate (SL) diastasis primarily comes from plain radiographs and arthroscopy. The clinical implications of SL diastasis are not clear. The aim of this study is to describe fracture characteristics of distal radius fractures on computed tomography (CT) scans in patients with distal radius fractures and static SL diastasis. Methods  We queried our institutional databases to identify patients who were treated for a distal radius fracture, had a CT scan with a wrist-protocol, and static SL diastasis on their CT scan. Our final cohort consisted of 26 patients. We then collected data on their demographics, injury, treatment, evaluated injury patterns, and measured radiographic SL characteristics. Our study cohort consisted of 11 men (42%) and almost half of our cohort ( n  = 12; 46%) had a high-energy mechanism of injury. The majority of the patients ( n  = 20; 77%) had operative treatment for their distal radius fracture and two patients (7.7%) had operative treatment of their SL injury. Results  The mean SL distance was 3.5 ± 1.1 mm. Twenty patients (77%) had an intra-articular fracture. In these patients, we observed three patterns: (1) scaphoid facet impaction; (2) lunate facet impaction; and (3) no relative impaction. We observed other injury elements including rotation of the radial styloid relative to the lunate facet and partial carpal subluxations. Conclusion  Static SL dissociation in the setting of distal radius fractures may be an indication of a complex injury of the distal radius, which may not be directly apparent on plain radiography. If these radiographs do not demonstrate impaction of the lunate or scaphoid facet, a CT scan may be warranted to have a more detailed view of the articular surface. Level of Evidence  This is a Level III, diagnostic study.

[Special aspects of fractures of the distal forearm]

BACKGROUND

Fractures of the distal forearm, especially fractures of the distal radius which are the most common fracture in humans, are of increasing socioeconomic relevance due to the increasing incidence and the increasing costs that are associated with the popularity of palmar plating.

OBJECTIVES

Radiological imaging for diagnosis and follow-up are presented with special focus on new biomechanical fracture concepts such as the four-corner concept.

MATERIALS AND METHODS

The basic literature and expert opinions are evaluated and discussed.

RESULTS

In intra-articular fractures of the distal radius, plain radiographs must be supplemented by computed tomography (CT). Direct CT arthrography allows not only analysis of the fracture pattern, but also detection of accompanying injuries of the carpus, especially the scapholunate ligament, and the ulnocarpal complex. The plain radiographs should also be analyzed for accompanying injuries. Therefore, both acquisition of the imaging data and their morphometrical analysis have to be standardized.

CONCLUSIONS

In addition to diagnosis and follow-up, radiological imaging plays a decisive role in the treatment of distal forearm fractures. CT and direct CT arthrography have become important tools in intra-articular distal radius fractures.

Three-dimensional analysis of displacement characteristics of dorsally angulated intra-articular distal radial fractures

Understanding the complex fragmentation of intra-articular distal radial fractures contributes to achieving anatomical reduction during surgery. This study aimed to clarify three-dimensional displacement patterns of intra-articular fragmentation in dorsally angulated, intra-articular distal radial fractures. We identified five characteristic intra-articular fragments: a key fragment, dorsal ulnar corner, dorsal wall, radial column and anterior radial column. The key fragment was displaced with radial deviation, pronation and extension and with dorsal, proximal and radial translations. The dorsal ulnar corner displacement resulted in a gap, a step-off and a deepened concavity for the lunate facet and sigmoid notch. The dorsal wall displacement resulted in a deepened concavity, a gap and a step-off of the dorsal scaphoid facet. The displacements of the radial column and anterior radial column caused a step-off between the scaphoid and lunate facets. The five characteristic intra-articular fragments each created a characteristic gap and step-off in the articular surface. Level of evidence: IV.

Biomechanical considerations on a CT-based treatment-oriented classification in radius fractures

A wide range of different classifications exist for distal radius fractures (DRF). Most of them are based on plane X-rays and do not give us any information on how to treat these fractures. A biomechanical understanding of the mechanical forces underlying each fracture type is important to treat each injury specifically and ensure the optimal choice for stabilization. The main cause of DRFs are forces acting on the carpus and the radius as well as the position of the wrist in relation to the radius. Reconstructing the mechanism of the injury gives insight into which structures are involved, such as ruptured ligaments, bone fragments as well as the dislocated osteoligamentous units. This article attempts to define certain key fragments, which seem crucial to reduce and stabilize each type of DRF. Once the definition is established, an ideal implant can be selected to sufficiently maintain reduction of these key fragments. Additionally, the perfect approach is selected. By applying the following principles, the surgeon may be assisted in choosing the ideal form of treatment approach and implant selection.

When a volar locking plate is not the right choice in fractures of the distal radius: Case based technical considerations

A volar approach is commonly used for fixation of distal radius fractures with a volar locking plate. There are certain fracture patterns for which volar locked plating is not suitable. This case based review outlines such case examples.

Fracture lines and comminution zones in OTA/AO type 23C3 distal radius fractures: The distal radius map

OBJECTIVE

This study was designed to define fracture lines and comminution zones in OTA/AO 23C3 distal radius fractures from axial computed tomography (CT) images that would influence surgical planning, development of new classifications, and possible implant designs.

METHODS

Thirty-four consecutive OTA/AO 23C3 fractures treated by a single surgeon between January 2014 and December 2014 were analyzed. For each fracture, maps of the fracture lines and zones of comminution were drawn. Each map was digitized and graphically superimposed to create a compilation of fracture lines and zones of comminution. Based on this compilation, major and minor fracture lines were identified and fracture patterns were defined.

RESULTS

All major fracture lines were distributed in the central region of the radius distal articular surface. There is a recurrent fracture pattern with a comminution zone including the scaphoid and lunate fossa; Lister's tubercle; and ulnar, volar, and radial zones.

CONCLUSION

It is important for the practicing surgeon to understand these four main fragments. Knowledge of this constant pattern should influence the development of new classifications and possible implant designs.

Association of scapholunate dissociation and two-part articular fractures of the distal radius

Scapholunate dissociation may occur in association with distal radial fractures and is easily missed at initial presentation. The aim of this study was to examine variances in the scapholunate distance with respect to subtypes of two-part partial articular distal radial fractures. Axial computed tomography (CT) scans of acute two-part intra-articular radial fractures were assessed retrospectively from 80 patients and compared to 20 controls. From each scan, two images were analysed to identify the scaphoid, lunate and articular fracture line in the distal radius for fracture type categorization. The images were overlaid on a standardized distal radius template and the scapholunate distance measured. Significant increase in the scapholunate distance was noted in fracture subtypes: radial styloid oblique; dorsal ulnar column; sagittal ulnar column; and volar coronal. We conclude that these findings support the need for a higher index of suspicion for scapholunate dissociation in these distal radial fracture subtypes. Level of evidence: III.

Microstructure of the Distal Radius and Its Relevance to Distal Radius Fractures

Background  There is a paucity of information on the microstructure of the distal radius, and how this relates to its morphology and function. Purpose  This study aims to assess the microanatomical structure of the distal radius, and relate this to its morphology, function, and modes of failure. Methods  Six dry adult skeletal distal radii were examined with microcomputed tomography scan and analyzed with specialist computer software. From 3D and 2D images, the subchondral, cortical, and medullary trabecular were assessed and interpreted based on the overall morphology of the radius. Results  The expanded distal radial metaphysis provides a wide articular surface for distributing the articular load. The extrinsic wrist ligaments are positioned around the articular perimeter, except on the dorsal radial corner. The subchondral bone plate is a 2 mm multilaminar lattice structure, which is thicker below the areas of the maximal articular load. There are spherical voids distally, which become ovoid proximally, which assist in absorbing articular impact. It does not have Haversian canals. From the volar aspect of the lunate facet, there are thick trabecular columns that insert into the volar cortex of the radius at the metaphyseal-diaphyseal junction. For the remainder of the subchondral bone plate, there is an intermediate trabecular network, which transmits the load to the intermediate trabeculae and then to the trabecular arches. The arches pass proximally and coalesce with the ridges of the diaphyseal cortex. Conclusion  The distal radius morphology is similar to an arch bridge. The subchondral bone plate resembles the smooth deck of the bridge that interacts with the mobile load. The load is transmitted to the rim, intermediate struts, and arches. The metaphyseal arches allow the joint loading forces to be transmitted proximally and laterally, providing compression at all levels and avoiding tension. The arches have a natural ability to absorb the impact which protects the articular surface. The distal radius absorbs and transmits the articular impact to the medullary cortex and intermediate trabeculae. The medullary arches are positioned to transmit the load from the intermediate trabeculae to the diaphysis. Clinical Relevance  The microstructure of the distal radius is likely to be important for physiological loading of the radius. The subchondral bone plate is a unique structure that is different to the cancellous and cortical bone. All three bone types have different functions. The unique morphology and microstructure of the distal radius allow it to transmit load and protect the articular cartilage.

[Descriptive, radiographic, topographic and functional anatomy applied to distal radius fractures]

Extensive anatomical knowledge is needed in order to correctly treat distal radius fractures: normal and pathological osteology of the distal radius, distal radio-ulnar joint and radiocarpal joint-both on the descriptive and functional level-the neurovascular and muscular environments of the distal radius-which are essential to the surgical approaches-and the angles that need to be restored during the reduction. All of these concepts are broached in this article.

Four-Corner Concept: CT-Based Assessment of Fracture Patterns in Distal Radius

Operative treatment using plate fixation is an important adjunct in the treatment of distal radius fractures, although the evidence for its superiority over other modalities remains limited. We propose a new concept for fractures of the distal radius, based on the three-column model of the distal radius, and on the expanding knowledge about the different fracture patterns obtained by evaluation of the distal radius by computed tomographic (CT) scan. All fracture types can be characterized by subdividing the wrist joint into four corners, each with its own characteristics in terms of mobility, stability, and transfer of forces in the intact distal radius. Recognition of the specific fracture types based on this four-corner concept enables a tailored approach to treatment.